It’s pretty. By default, even. Floorp is customizable, but many (most) people want a tool that works directly out of the box, and if it looks good while doing it, then it will be more popular.

The dev advertised it on Reddit, then when people complained about issues, you would see a response from them along the lines of “fixed,” which showed responsiveness, and I think that gained loyalty before the product was ready to be released.

This is a pretty difficult question to answer since all phenomena are quantum. A star is powered by nuclear (quantum) fusion. Permanent magnets depend on the quantized angular momentum of electrons. Could these phenomena be allowed by something other than quantum mechanics? Maybe. But a constant goal of science is to find the simplest explanation for all we observe, meaning that whatever alternative explanations you come up with, should they be correct, then taking them all together will constitute a theory that at least looks an awful lot like matter waves (mathematically, at least).

The critics of Ukrainian use of the mines appear to be protestors. In theory, they could also protest the Russian use, but it’d be a bit silly to picket against an invasion regardless (unless your government is the one invading).

The idea is that land mines are indiscriminate and long-lasting, so they should not be used by either side regardless of the other’s stance. They’re a bit like anti-nuclear protests, I think.